Dark Skies
Star clusters in the large Magellanic cloud.
When was the last time you saw the Milky Way? A shooting star? Do you have trouble sleeping at night when there are bright lights from neighborhood homes or businesses pouring into your bedroom windows? Many people are becoming aware that although electric lighting is wonderfully beneficial at night, uncontrolled light can contribute the light haze that obscures the stars. Uncontrolled electric light can also be ugly, distracting, and may disrupt our sleep. It may also affect the wildlife sharing our environment.
What can be done about it? Careful design of outdoor lighting and outdoor lighting products is an important step. Effective light fixtures put their light where it is wanted and needed, and DOESN'T put it where it's not. As an example, many decorative "acorn" top streetlights look attractive during the day, but at night they become glaring to drivers and residents, as well as sending almost half of their light upward into the skies. This uplight looks very pretty when you are in an airplane overhead, but every dot of light you see out the window of a plane is also contributing to light pollution. A better alternative is a decorative streetlight that sends almost all of its light downward, toward the pavement and walkways.
Tilted-head parking lot fixtures, sports field lighting equipment, gas stations canopies, and uplighting of buildings and landmarks are additional sources of upward light. Should we eliminate these? Sometimes, the answer is clearly "YES!" when there are easy alternatives that deliver light where it's needed without polluting the skies. But it's not always that simple. Fixtures with better optical control are often more expensive. Gas station owners may argue that if you eliminate the glare, you also eliminate the perception of safety for customers. Municipalities may argue that uplighting of monuments and historic buildings helps bring people downtown for concerts, restaurants and nighttime festivals. The light helps people feel safer while they are enjoying the cultural history the buildings or bridges or monuments represent.
Obviously there is no easy answer, but we can design with light pollution and light trespass (unwanted light on neighboring properties) in mind. Sometimes the solution is turning off the decorative lighting at 10pm using timeclocks. Sometimes the solution is shutting off half or more of the lighting in a parking lot after the second shift has gone home at midnight. Façades can be lit with fixtures that are carefully louvered so that no light is emitted directly into the sky, and sometimes that façade can be attractively lighted from the top of the building downward, instead.
Electric light can be very beneficial. Let's use it responsibly, but turn it off whenever we can, so that our kids can enjoy seeing Orion in the wintertime, and experience the thrill of spotting a shooting star.